1. Field of the Invention
The present invention relates to a scroll compressor and an air-conditioning system for a vehicle using the scroll compressor.
2. Description of the Related Art
A scroll compressor is used, for example, in the refrigeration circuit of an air-conditioning system for a vehicle. The compressor has a scroll unit contained in a housing thereof and the scroll unit includes a fixed scroll and a movable scroll. Each of the scrolls has a base plate and a spiral wall integral with the base plate. The scrolls are engaged with each other and the spiral walls have respective sliding surfaces in sliding contact with each other's base plates.
Also, a revolving unit is arranged in a drive chamber defined in the housing. Specifically, the revolving unit is located between one inner end wall of the housing and the scroll unit and causes the movable scroll to make revolving motion relative to the fixed scroll. As the movable scroll revolves, the scroll unit performs a series of processes including the suction, compression and discharge of working gas. A discharge chamber, into which the compressed working gas is discharged from the scroll unit, is defined between the other inner end wall of the housing and the scroll unit.
This type of scroll compressor uses, as working gas, a refrigerant containing lubricating oil, and the lubricating oil, if circulated through the refrigeration circuit, lowers the refrigerating capacity of the circuit. To avoid the inconvenience, the scroll compressor disclosed in Unexamined Japanese Patent Publication No. H11-82335, for example, has a separating chamber and an oil chamber, both adjoining the discharge chamber. The lubricating oil is separated from the compressed working gas in the separating chamber and then is stored in the oil chamber. The compressor further includes an oil feed hole extending through the fixed scroll, and the oil feed hole permits only the lubricating oil to be returned to the revolving unit therethrough.
In this conventional compressor, however, the oil feed hole opens in the sliding surface of the fixed scroll, and the opening of the oil feed hole is periodically covered with the base plate of the revolving movable scroll. While the opening is covered with the base plate, the quantity of lubricating oil supplied to the drive chamber through the oil feed hole decreases, hindering the supply of the lubricating oil to the revolving unit. Further, while the opening of the oil feed hole is covered with the base plate, the flow velocity of the lubricating oil in the oil feed hole lowers. Thus, when the opening is uncovered thereafter, the lubricating oil ejected from the opening into the drive chamber may fail to be satisfactorily atomized. With the conventional compressor, therefore, it is possible that the revolving unit is supplied with an insufficient quantity of lubricating oil or that the lubricating oil fails to spread throughout the drive chamber, that is, the revolving unit, due to poor atomization of the lubricating oil.